{"nrhp_refnum":"99001319","name":"Old State Road Bridge","other_names":["Bin #3-335596-0"],"category":"structure","location":{"address":"Co. Rt. 17B over AuSable R.","address_restricted":false,"city":"AuSable Chasm","county":"Clinton County","state":"NY","lat":44.523584424000035,"lon":-73.45975630299995,"geom_source":"nps_gis"},"listed_date":"1999-11-12","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Transportation","Engineering"],"significance_levels":["local"],"summary":{"what_it_is":"A single-lane steel Pratt pony truss bridge built c.1890 that carries County Route 17B over the AuSable River in the hamlet of AuSable Chasm, Clinton and Essex Counties, New York.","why_significant":"The nomination argues it is an intact, well-preserved example of late-19th century bridge engineering and construction. It also played a role in local and regional transportation, linking the hamlet across the river and carrying a major north-south route until the 1930s.","narrative":"Spanning the AuSable River in the hamlet of AuSable Chasm, this one-lane steel Pratt pony truss bridge dates to about 1890. It measures 107 feet in a continuous span with a central stone pier, and a cantilevered walkway on the west side offers a view of Rainbow and Horseshoe Falls. Its builder and exact date are unknown. The bridge replaced a succession of wooden crossings whose timbers decayed in the damp mist from the falls. It was built as local industry declined and tourism grew. Until the 1930s it carried NYS Route 9, a major north-south route, but increasing automobile and truck traffic made its light-load, single-lane design obsolete. Route 9 was realigned and the 1932 AuSable Chasm Bridge took over through traffic. The older bridge has since served local traffic only. It was listed for its engineering value as a well-preserved late-19th century truss and for its role in local and regional transportation.","period_of_significance":"c.1890-1948","architect_builder":null,"architectural_style":"Pratt pony truss bridge (steel)","criteria":["A","C"],"status_note":"Still carries local traffic as a secondary crossing; original wood deck replaced with steel grating but otherwise retains much of its original appearance and integrity.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:51:50.121884-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_NY/99001319.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/99001319/ee6e132754-800.webp","url_1600":"https://nationalhistoricalregister.com/media/99001319/ee6e132754-1600.webp","licence":"CC BY-SA 4.0","author":"Magicpiano","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:AusableChasmNY_OldStateRoadBridge.jpg\" rel=\"noopener\">Magicpiano</a>, <a href=\"https://creativecommons.org/licenses/by-sa/4.0\" rel=\"license noopener\">CC BY-SA 4.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:AusableChasmNY_OldStateRoadBridge.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/75312363","wikipedia":"https://en.wikipedia.org/wiki/Old_State_Road_Bridge","wikidata":"https://www.wikidata.org/wiki/Q7085090"},"indexable":true,"url":"https://nationalhistoricalregister.com/new-york/clinton-county/old-state-road-bridge-99001319/"}